Surface Morphology-Dependent Photodetection of the Magnetron-Sputtered Nb-Doped BaTiO ₃ Ferroelectric Thin Film Device

In this study, Nb-doped BaTiO3 thin films were deposited on a p-type Si substrate (p-Si/n- BaTi0.93Nb0.07O3/Ag) by radio frequency magnetron sputtering under varied synthesis conditions to investigate their structural, ferroelectric, and photodetection properties. XRD confirms phase-pure perovskite films, while SEM and AFM show variation of the grain size and roughness profile of the samples. Ferroelectric polarization was verified through P–E loop measurements that show differences in remanent polarization that directly affect the carrier separation efficiency. Current–voltage characterization demonstrates rectifying diode behavior with markedly higher photocurrent in reverse bias. Photoresponse analysis revealed that the optimized device with the device structure p-Si/BTNb/Ag exhibited the highest figure of merit, which shows the best performance with external quantum efficiency (EQE) = 38%, responsivity = 0.13 A/W, and detectivity = 1.6 × 1011 Jones, owing to strong ferroelectric polarization and balanced leakage. These results establish p-Si/n-BTNb/Ag heterostructures as promising ferroelectric photodetectors with a tunable performance governed by microstructural and ferroelectric polarization.